Answer
A' = {6,7,8,9... 20}
Work Step by Step
U = {1,2,3,4...20}
A = {1,2,3,4,5}
The set A' contains the elements that are not present in the set A.
The elements of set A i.e. 1,2,,3,4,5 must not be present in set A.
The elements of A' are 6,7,8,9, ... 20.
Therefore A' = {6,7,8,9... 20}.
